LETTER TO JMG

A tRNA^Ala mutation causing mitochondrial myopathy clinically resembling myotonic dystrophy

R Horváth^1,*, H Lochmüller^2,*, C Scharfe³, B H Do³, P J Oefner³, J Müller-Höcker⁴, B G Schoser², D Pongratz², D P Auer⁵, M Jaksch¹

¹ Metabolic Disease Centre Munich-Schwabing, Institutes of Clinical Chemistry, Molecular Diagnostics and Mitochondrial Genetics; Academic Hospital Schwabing, Munich; Germany
² Friedrich-Baur-Institut, Department of Neurology, Ludwig-Maximilians-University, Munich, Germany
³ Stanford University, Genome Technology Center, Palo Alto, CA, USA
⁴ Institute of Pathology, Ludwig-Maximilians-University, Munich, Germany
⁵ Max Planck Institute of Psychiatry, Munich, Germany

Correspondence to:
Correspondence to:
Dr M Jaksch
Metabolic Disease Centre Munich-Schwabing, Institutes of Clinical Chemistry, Molecular Diagnostics and Mitochondrial Genetics, Academic Hospital Schwabing, Kölner Platz 1, 80804 München, Germany; Michaela.Jaksch@lrz.uni-muenchen.de

Keywords: mitochondrial DNA mutation; myotonic dystrophy; ragged red fibres; respiratory chain deficiency

The first 150 words of the full text of this article appear below.

More than 100 pathogenic mitochondrial (mt) DNA mutations have been described in the past decade in association with different neuromuscular disorders. Apart from large scale mtDNA rearrangements and common point mutations in mt tRNA genes, pathogenic mutations affecting structural genes of mtDNA encoded respiratory chain subunits have been reported as well.¹

Pathogenic tRNA mutations can affect translation of respiratory chain (RC) complexes that are partly encoded by the mtDNA, that is, complexes I, III, and IV. The most common tRNA mutation is associated with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) and is located in the tRNA^Leu(UUR) gene. So far, 13 additional pathogenic mutations have been described in this gene in association with different neurodegenerative disorders. Similarly, mutations in tRNA^Ile, tRNA^Lys, and tRNA^Ser(UCN) are known to cause various mitochondrial encephalomyopathies or non-syndromic deafness (see Mitomap http://www.mitomap.org/). The remaining 18 mitochondrially encoded tRNAs are rarely reported to . . . [Full text of this article]

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• Kiyomoto, B H, Tengan, C H, Costa, C K, Oliveira, A S, Schmidt, B, Gabbai, A A (2006). Frequency of dystrophic muscle abnormalities in chronic progressive external ophthalmoplegia: analysis of 86 patients. J. Neurol. Neurosurg. Psychiatry 77: 541-543 [Abstract] [Full Text]  
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